STERLING – The Rock Falls Rockets' plan was to put the pedal to the floor from the opening point Tuesday against Princeton in the semifinals of the Class 3A Sterling Regional.

Rock Falls did just that for the first game and half of the second in a 25-13, 25-19 win. The Rockets (26-10) advance to play Sterling on Thursday in the regional final.

It was the let-up near the end of the second game that weighed on coach Sheila Mammosser's mind.

"Our plan was to be aggressive, and we did that until the end of the second set," Mammosser said. "I am not sure what happened then, but we let up and they started coming back.

"You can't afford to let up at this point of the season. All it takes is a point here or a point there and it will be over. If we play like we did tonight on Thursday, it will be a short night. Sterling is too good to play like that."

The Rockets raced out to a 15-6 lead in the second set. Jordan Giddings and Linsey Brown each had three kills for the Rockets in that run.

Slowly, Princeton started to rally, drawing as close as three points at 21-18. The teams traded points before Brown had a kill, followed by two kills from freshman Bailey O'Brien to end the match. All three points were assisted by Addesyn Nailor.

"We wanted to prove to everyone at this regional that we are a better team than we were earlier in the season," Brown said. "We wanted to show that we are capable of beating any team we play against."

The first set stayed close through the first 15 points, but the Rockets pulled away after that as they fed Giddings in the middle.

The senior middle hitter spiked two kills in a row to put Rock Falls up 15-8, and then had a big block after a sideout to set the tone for the rest of the game.

Giddings finished with eight kills.

"That's what we should do with a 6-foot-1 middle hitter that can dominate like she can," Mammosser said. "We set her to open things up for everyone else. We have five girls that can come up and really hit the ball."

Brown had eight kills and 10 service points. Nailor led the team with 13 assists. Morgan Mammosser, the 2011 SVM player of the year, finished with six assists, four kills and two aces.

Michelle Kelly had eight assists for Princeton. Emmalee Sears and Ashley Farraher each had three kills.